1. Field of the Invention
The present invention relates to a connector used for connecting wiring harnesses and more particularly to a connector structure having a terminal locking block mounted to a connector housing to prevent terminal lugs inserted into the terminal accommodating chambers in the connector housing from slipping off backwardly.
2. Prior Art
A general practice of locking the terminal lugs inserted into the terminal accommodating chambers in the connector housing is by forming flexible engagement pieces integral with the inner walls of the terminal accommodating chambers and then engaging the terminal lugs inserted into the chambers with the flexible engagement pieces to prevent the terminal lugs from slipping off backwardly from the terminal accommodating chambers. In recent years, there has been proposed a structure in which a terminal locking block is mounted to the rear part of the connector housing so that the terminal locking block, either in combination with or in place of the flexible engagement pieces, can reliably prevent the slip-off of the terminal lugs.
FIG. 6 shows an example of a conventional connector structure. A connector housing a has a provisionally-engaging projection b and a full-engaging projection member c formed on the rear part of the outer circumference thereof, with two projections spaced a short distance axially. In a provisionally-engaged condition in which a pair of coupling frames e of a terminal locking block d are engaged with the provisionally-engaging projection b, a terminal lug g already connected with a wire is inserted into a terminal accommodating chamber h through an opening in a base frame f of the terminal locking block d.
The base frame f has, in addition to the paired coupling frames e, a pair of flexible terminal holding pieces i which are disposed parallel to the paired coupling frames e. In the provisionally-engaged condition, the terminal holding pieces i are out of the terminal lug insertion path.
Next, the terminal locking block d is pushed forwardly to engage the coupling frames e with the full-engaging projection member c. In this full-engaged condition, free end portions i.sub.1 of the terminal holding pieces i are guided along a tapered drive wall j so that they are curved inwardly to engage with the terminal lug g, thus preventing the backward slip-off of the terminal lug (see FIG. 7).
In the above construction, when an extraneous force as from hand or foreign matter is applied inadvertently to the terminal locking block d in the provisionally-engaged condition, the terminal locking block d may be shifted into the full-engaged condition. When, on the other hand, one wants to pull out the terminal lug g by shifting the terminal locking block d from the full-engaged condition back to the provisionally-engaged condition, the terminal lug g may get caught by the free end portions i.sub.1 of the terminal holding pieces i that underwent plastic deformation along the tapered drive wall j.